Twist like SimplerDeform but with bones?
I would try to use a bendy bone with controllers (see here), then add a bone at the base of the bendy bone (I'll call it "rotator" from now on). The opposite bendy bone's controller will be parented to the rotator, and its rotations will also be driven by the rotator.

In theory, this will make the opposite controller rotate arround the bendy bone base and rotate it twice the amount of the rotator's rotation. The bendy bone would form a perfect half-circle shape, without any wrong deformation.

Duplicate the whole thing and invert it to get the other half, and you have your simple-deform-like rig.

I did a test, you can download and retro-engineer it.